The present invention relates generally to a restraint system that has general application to slidable, non-fixed vehicular seats.
The typical seat used in many large trucks or in other heavy vehicle applications is shown in FIG. 1. This seat 10 comprises a seat portion 12 and a back portion 14. The seat is movable vertically as well as horizontally. The seating surface is supported by a support structure generally shown as 20 having a crossbar construction 22, a lower frame 24 secured to the floor 26 of the vehicle and an upper frame member 28. Those skilled in the art will recognize that the crossbars are slidable within the frames 24 and 28. The upper frame member 28 defines part of a track to loosely receive a track portion 30 secured to the seat. In this way the seat 10 is slidably mounted relative to the support 20. In many automotive applications a typical seat can be moved fore and aft by a motorized or mechanical system. Once moved the seat is locked in its new position. This is not the case in large truck type seating applications in which the seat is not fixed in the horizontal direction (see arrow 27) and is free to move or oscillate plus or minus 2.5, 5.0 or more centimeters in response to the inertial forces and occupant forces imparted thereto.
As mentioned above, the seat is also vertically adjustable. Typically these seats include an air spring generally shown as 31 connected between the two crossbars or frame portions 24 and 28 and a small shock absorber 32 to provide damping to prevent excessive oscillation (see arrow 33) of the seat during an accident. The air spring is connected to a source of pressurized air to permit the vertical movement of the seat under operator control. The seat is tethered to the floor 26 of the vehicle by one or more tethers 34a and 34b attached to the rear sides of the seat portion 12. Typically these tethers are lengths of seat belt material. As can be appreciated, these tethers are only effective during an emergency to restrain the forward motion of the seat if the seat is in its most forward position and the tether 34a and 34b are relatively taut. A deficiency in this type of system is that a larger sized driver or occupant of the vehicle will typically position the seat rearward of that position used by a smaller occupant or driver. With the seat in this more aft position, and as illustrated in FIG. 1, the tethers 34a and b are not taut but have slack. During a frontal collision this occupant may not be fully protected as the seat will first move forward due to the inertial forces generated during the crash and will not be restrained until the tethers 34a and b are pulled taut. Further, as can be appreciated, the seat 10 as well as the occupant are susceptible to higher acceleration loading and resulting impact forces since the seat 10 is permitted to move forward due to the limited restraint potential of this type of system.
It is an object of the present invention to provide a system to restrict the forward motion of the seat structure during a crash regardless of position of the seat prior to the crash. A further object of the invention is to provide a device which will eliminate any slack in a flexible retaining member linked to the seat or to pre-load the flexible member subsequent to a crash to more retain the seat in a rearward position.
Accordingly, the invention comprises: a safety system comprising: an occupant seat having a seating portion and first means for slidable supporting the seat portion such that the seat is permitted to freely move in a fore and an aft direction in response to forces imparted thereto; and first restraint means, maintaining a flexible member in a taut condition as the seat is moved fore and aft and activated during an emergency for restraining the seat from moving forward from a pre-emergency position. The flexible member is joined at one end to a structural part of the seat and at another end to a tensioning means for maintaining the flexible member in a generally taut condition as the seat is moved fore and aft. In one embodiment of the invention the tensioning means includes a spring loaded, rotary spool having the flexible member wound thereabout and means, activated during an emergency, for preventing the protraction of the flexible member from the spool. In another embodiment the tensioning means includes a linear acting spring loaded piston. Still in another embodiment a pretensioning device is used to eliminate any slack in the flexible member and to also move the seat rearward and maintain the seat in its moved position.
Many other objects and purposes of the invention will be clear from the following detailed description of the drawings.